A wide variety of coffee brewing devices are well known in the art. One such device comprises a housing for a water tank, the tank having an inlet in the top thereof connected to a receiving tray. The tank is also provided with a siphon extending generally from the top thereof outwardly terminating in a spray head located above a funnel having coffee grounds supported therein on a filter paper. Another well known form of coffee brewing device substitutes a water overflow tube for the siphon, the tube being connected to the aforesaid spray head.
In operation, water is added to the tank up to the level of the discharge conduit whether it be a siphon or an overflow tube and the heater energized until the water in the tank reaches the desired coffee brewing temperature. The coffee brewer is now in condition to be employed to brew coffee. In order to brew coffee, cold make-up water is poured into the receiving tray from whence it passes gravitationally downwardly through an antidiffusion tube to the bottom of the tank thereby forcing the preheated water therein upwardly by displacement with little mixing of hot and cold water. As the level of the preheated water rises in the tank, it passes into the siphon or overflow tube and from thence to a spray head over a funnel containing ground coffee supported on a filter.
The volume of water discharged through the spray head is equal to the volume of cold make-up water added to the tank provided that the water level in the tank initially is immediately beneath the entrance to the siphon or overflow tube.
Such coffee brewers are generally adapted only for the discharge of relatively large quantities of water sufficient to make a full pot of fresh coffee. They are not adapted for the discharge of smaller, controlled quantities of hot water for use as make-up for tea, soups, hot chocolate or other beverages or liquid foods.
Moreover, if the heated water in the tank remains unused for more than a few hours, evaporation lowers the water level in the tank. Consequently, the volume of hot water discharged through the spray head is less than the volume of cold make-up water added which adversely affects the quality of the coffee brewed. The level of the water in the tank is not visible from outside of the tank. Therefore, one can never be certain as to whether or not a sufficient quantity of cold make-up water has been added to achieve the desired amount of coffee. Additionally, if an excessive quantity of cold make-up water is required to compensate for evaporation, the mean temperature of the water discharged for brewing may be lower than that desired.
Therefore, there is great need in the art for a coffee brewer which provides means for dispensing relatively small, limited but controlled quantities of hot water without adversely affecting the volume of hot water immediately available for brewing purposes as well as means for continuously replacing water lost through evaporation.
It is among the objects and advantages of the present invention to provide such a coffee brewer which includes a separate and preferably removable water supply reservoir adapted for dispensing lesser but controlled quantities of hot water from a separate, valve controlled discharge conduit.
Still another object of the present invention is to provide a coffee brewer with means for dispensing controlled quantities of hot water less than the volume necessary for brewing a full pot of coffee in which make-up water from a separate reservoir is automatically supplied in the precise quantity withdrawn without resort to mechanical valves between the said reservoir and the water heating tank from which the hot water is withdrawn.
Yet another object of the present invention is to provide the reservoir aforesaid with closure means to prevent unwanted or inadvertent gravitational discharge of water until it is placed a normal operating position in association with a coffee brewer and including opening means for automatically opening the reservoir means when the reservoir is placed in its normal operating position.